1. Field of the Invention
The invention concerns an introducer sheath for inserting a catheter into a circulatory vessel, such as the femoral artery. The introducer sheath prevents obstruction of the vessel and thus eliminates the risk of ischemia, tissue hypoxemia, and thrombosis. The invention further concerns a percutaneous method for inserting the introducer sheath, and a means by which the catheter can be securely anchored in the blood vessel so as its side holes not to move relative to the blood vessel's main lumen and the distal blood flow remains uninterrupted.
2. Description of the Related Art
The development of miniaturized surgical instruments and probes has resulted in an increase in the popularity of non-invasive surgery.
For example, percutaneous translumenal coronary angioplasty involves the percutaneous introduction of an inflatable balloon tipped catheter assembly into the femoral artery and its advancement, distally, through the arterial system to the situs of, e.g., an atherosclerotic lesion. The balloon is then inflated to dilate the constricted vessel.
Another surgical technique, intra-aortic balloon pump (IABP) counterpulsation, provides circulatory assistance to a patient experiencing a cardiogenic shock. Using a needle, a guide wire and a dilator sheath assembly, an elongated catheter-mounted balloon pump is inserted percutaneously through an introducer sheath into a femoral artery, and the assembly travels through the abdominal aorta towards the heart and is positioned into the descending thoracic aorta. After the pump is properly positioned in the thoracic aorta it is inflated and deflated phased with the patient's ECG in a manner to produce diastolic counterpulsation. The intra-aortic balloon thereby functions as a pump, assisting the flow of blood through the coronary and carotid arteries in diastole and to the body during balloon deflation.
Despite advances in non-invasive surgery, techniques such as intra-aortic balloon pump counterpulsation remain hazardous. The introducer sheath, through which the balloon tipped catheter must pass, obviously has a larger outer diameter than the outer diameter of the balloon tipped catheter. Particularly in females, which generally have smaller diameter arteries, and patients with peripheral vascular disease, these introducer sheaths can block blood flow, causing arterial thrombosis. Further, the devices may, in some instances, remain in the body for extended periods of time, i.e., several days or more. Special precautions must thus be taken to prevent the introducer sheath or guide cable from blocking or restricting blood flow through the femoral artery. Loss of blood flow to the lower extremities results at a minimum in ischemia and localized tissue anoxemia, and in severe cases can result in amputation of the patient's leg.
One prior art technique for reducing the risk of circulatory blockage involved the use of a double lumen catheter with an inner lumen for injection of dyes, monitoring blood pressure, etc, and with an outer crescent shaped outer lumen with one side hole, as disclosed in the U.S. Pat. No. 4,755,176. However, when using such a design the single side hole could be completely blocked and sealed by atheromatous plaques within the intima of the femoral artery, leading to thrombosis of the second or outer crescent shaped channel. Further, this teaching concerns a catheter and not an introducer sheath.
Yet a further problem with an emplaced introducer sheath is the tendency for the sheath to move relative to the blood vessel's main channel, diverting the fenestrations' blood streams to the sidewall of a small female gender type of artery such that the distal blood flow will be stopped.
While the above mentioned patents are representative of the designs which have been developed to provide catheters or introducer sheaths for introducing catheters into bodily vessels, each clearly has inherent problems, limitations and disadvantages.